Electric arc lamp



- June 2, 1931.

o. KRELL ETAL 8,558

ELECTRIC ARC LAMP F'iled Aug. 17, 1927 3 Sheets-Sheet l June 2, 1931. o. KRELL ET AL ELECTRIC ARC LAMP Filed Aug. 17,, 1927 5 Sheets-Sheet 2 June 2, 1931. o. KRELL ET AL ELECTRIC ARC LAMP Filed Aug. 1'7, 1927 3 Sheets-Sheet 3 Patented June 2, 1931 i 8 UN ITED STAT ES P'ATENT OFFICE OTTO KRELL, E BEBLIN-DAHLEH, AND HANS GEBiDIEN OF BEm-GRUNEWALD,

GERMANY, ASSIGNORS '10 SIEMENS-SCHUCKRTWEBK E .AKTIENG l 1 I 1 BERLm -SIEMENSSTADT, GERMANY, A CORPORATION 0! 6mm ELECTRIC no mun Application iiled August 17, 1927, Serial No. 213,602, and in Germany July 0, 1826.

Our invention relates to electric arc lamps. In order to attain high specific brilliancy in electric arc lamps it has already been r0- posed tosurround the positive electrode y a liquid-cooled revolving tube. The liquid, for instance water, is usually supplied to the tube axially and owing to the high rotary speed with a bore through w introduced.

of the tube thrown towards the outside, so that the interior and the end of the outer tube are covered with a continuous film of liquid.

According to our invention-the revolving tube is disposed coaxially with therotor of a motor. The rotor may then be directly cougled with the revolving tube and sensitive riving members eliminated. The rotor of the driving motor is referably provided ich the electrode is A number of embodiments of our invention are illustrated in the drawings aflixed hereto and forming part of our specification.

' In the drawings:

Fig. 1 illustrates a longitudinal section through an electric arc lamp in which the tube servin for limitin the contact area of the are on t e positive efiactrode, is' driven by an air turbine,

Fig. 1" represents an enlarged sectionalview of the central upper portion of Fig. 1

Fig. 2 represents a longitudinal section through an arc lamp in which the tube is driven by an electric motor,

Fig. 3 a similar section through an are 7 lamp in which the negative electrode is also cooled,

Fi 4 a partly sectional plan view of a searchlight in which the electrode-holder is secured by guywires, and

Fi 5 an end view of the search-light.

Re errin to Fig. 1 of the drawings which shows an e ectric arc lamp in which the tube serving for confining thefbase of the arc is driven by an air turbine. 1 is the negative electrode, 2 the protective tube which contains the positive electrode 1", and which is enamelled on its surface to prevent a flashover of the arc. The tube 2 is screwed on to a tubular shaft 3 journaled in the ball-bearings 4 and 5. Between these hearings is located the propeller wheel 6. 7 and 8 are hollow rings provided with bores at the sides facing the propeller wheel. Through the pi s 9 compressed air is supplied to the rings and 8 which issues through the bores 10 of the rings and sets the propeller wheel in rotation.

the ring, caught by the refractory ring 13, 4 consisting of graphite, for instance, and

hence flows into the interior of the standard 14of the lamp. To prevent the water from entering the interior of the driving mechanism splash-rings 15 and 16 are provided.

the turbine steam, compressed gas or water may be employed. When using steam or water a protective cap for discharging the driving medium issuing from the turbine must be jrovided.

o prevent damage to the tube in'case of failure of the driving mechanism which would interrupt rinsing and cooling of tube 2 with water, a device is provided by means of which the supply of current to the electrodes or the switching on of the current is prevented, when the speed of the tube 2 falls below a certain value or the tube stops alto ether.

With this endin view one or a plum it of spri 17 are fixed u on the pro eller w eel 6 an d l oaded with weights at their ends. In

the position of rest of the wheel 6 these s rings abut against the insulated ring 18.

en the blade wheel 6 has attained a sufficiently high speed the springs are raised ofi the ring 18 owing to the centrifugal force set up and the electric connection with the insulated ring 18 is interrupted. To render'the Instead of using compressed airlfor driving switching on of the current impossible when the tube 2 has come to rest the switch 19 is connected in the feeders to the electrodes. The switch lever of the contacting device is under the control of the 'electro-rn'agnet 20, the winding of which rece'ves current through the standard or casin 14 the ball-bearings, the spgring 17 and the insulated ring 18 as soon as t springs make contact with the insulated ring when the speed of the tubes 2 or 3 falls below a certain value. The switch lever is then pulled upwards and the supply of current mterrupte-d. The supply of current to the lamp remains interru ted until the tube 2 and the tubular shaft 3 ave attained a sufficient speed. V

Fig. 2 of the drawings illustrates a further embodiment of our invention in which the revolving tube is driven by an electric motor. 21 is a carbon electrode, 22 a revolving enamelled tube screwed to the hollow shaft 23 and serving for limiting the contact area of the are on electrode 21. The hollow shaft 23 carries the rotor 24 of an electric motor the field system 25 of which is housed in the easing 26. The hollow shaft 23 is journaled in the ball-bearings 27 and 28. 29 ls-a hollow ring supplied with water through the pipe 30 whlch is projected through the bores 31 into the interior of the tubular shaft 23. It traverses the hollowshaft and issues at theend of the electrode 21, is here thrown towards the outside, caught by the highly refractory ring 32 and discharged by the pipe 33. In order to lead the water supplied at the righthand end of the hollow shaft 23 safely to the left-hand end, the hollow shaft may at its inside be provided with helically wound grooves indicated by a dashed line. 34 and 35 are splash rings which prevent the penetration of 36 are contact members which electrically connect the electrode 31 with the housing. 37 is a feed device of any suitable design.

mechanical resistance.

The electric motor is preferably designed as series-woundmotorso that it may develop a high starting torque and be able to overcome In order to interrupt the suppl of current to the electrodes 21 and 39 when t e motor 38 is' at rest, a relay is preferably employed, which interrupts the supply if the current supplied to the motor exceeds or remains below a certain value. For this purpose the relay 40 is connected in the circuit of the motor 38 and closes the contacts 41 or 42 when the current in the circuit deviates form a predetermined value. The winding 43 is then energized and lifts the switch member 44 off its contacts and thus interrupts the Instead of designing the motor 38 as semes-wound motor, it may sometimes be prefferabl e to use a compound-wound motor. In

this way the maximum speed of the motor may. easily be limited by means of the shunt winding and the motor may yet develop a high startingtorque.

If alternatingcurrent is available for feeding the are lamp which is then preferablly first converted into direct current for fee ing the electrodes, it may be advantageous to design the motor 38 as a squirrel-cage rotor motor. In this Way the service is rendered more reliable, since the commutator,

the slip-rings and the like are eliminated and the armature may be made resistive to high temperatures. The stationary coil may easily be sufliciently cooled.

In certain cases the electric motor 38 may also serve for conveying the cooling liquid supplied to the tube 22. For this purpose ing of the negative electrode at high loads on the arc lamp, the negative electrode is also cooled according to another feature of our invention. If a turbine is used to drive the liquid-cooled tube surrounding the positive electrode, the driving medium discharged from the turbine may suitably be used for cooling the negative electrode or its holder.

Fig. 3 of the drawings illustrates an embodiment of our invention of this nature. Referring to this figure '45 is the positive electrode and 46 the negative-electrode. 47 is a liquid-cooled tube upon which is mounted the turbine runner 48. Through the nozzle ring 49 water is introduced into the interior ofthe tube 47. 50 is a ring of buckets to which is supplied the driving medium, such as compressed air, compressed gas or steam through the pipe 51 and the hollow ring 52. 53 and 54 are labyrinthpackings, which on the one hand prevent the penetration of wa-. ter into the turbine and on the other hand the leakage of any considerable quantities of the driving medium from the turbine. The driving medium escaping from the turbine is fed to the holder of the negative carbon throu h the hollow arm 56 electrically separate by insulation at any suitable place, for instance at 55. 57 are structural elements serving for the supply of current to the electrode 46. They are preferably arranged in the shape of a spider, if desired erforated, so that the cooling medium is ab e to sweep 9.1011 in the direction of the arc. 58 are openings through which the cooling medium passes into the atmosphere. Instead of these openings a special discharge conduit ma be provided to prevent with absolute'certamty the are from being interfered with by the draft of air. Should the quantity of driving which pass from the electrode holder to the neoaue 1 housing of the searchli'ght in the form of a spider at angles of'substantiall 120. The

rive of the electrodes may be e ected by thin shafts or spindles located in a plane with the guy members.

The electrode holder is preferably mounted withinthe searchlight in such a manner, that when the light cone is directed-horizontally the connecting arm 56 between the" positive and the negative "electrode holder 'lies horizontally or substantially so. Such an arrangement has the advantage that the arm 56 is -not located above the arc in any position of the Searchlight.

Figures; and 5 illustrate a Searchlight in which the electrode holders are held by guy wires. Fig. 4 shows the plan and Fig. 5 the end view 0 the arrangement.

Referring. to these figures 59 is the positive carbon, 60 the negative, 61 the positive carbon holder, and 62 the holder for the negative carbon. Both carbonholders are connected with each other by the arm 63, which is split at 64, the halves being electrically insulated. from each other. 65 is the proj ector or mirror, 66 the housing of the searchlight and 67 are guy wires from which the electrode holder is suspended. By exerting a perature fluctuations.

suflicient pull upon the wires a'sufliciently secure position of the electrodes may be at tained, particularlyif yielding members are inserted in the wires which maintain the necessary tension in these-members even when these members vary in length owing to tem- 68 and 69 are shafts I or spindles for feeding the carbons. 71 conmade without departing from tains the regulating device for the carbons. If the positive carbon is surrounded by a liquid-cooled tube which is driven by a gas or air turbine, the arm '63 may be made hollow and the driving medium escaping fromthe turbine may be used for cooling the holder of the negative electrode. This holder is then preferably provided with openings through which the cooling agent escapes into the atmosphere.

Various modifications and changes may be the sco of the invention;

' We 0 aim as our invention: v v 1. In an arc lamp in combination twoelectrodes and holders therefor, circuits. for connecting said electrodesto a current source, a motor, a tube spaced around the positive electrode and being directly coupled with said motor, and. means forsupplying cooling liquid into the space between said positive electrode. and said tube. V

2. In an arc lamp in combination two electrodes and holders therefor, circuits for connecting said electrodes to a current source, a motor,a tube spaced around the positive electrode and forming the rotor shaft for said motor, and means for supplying copling ing said electrode hol the spirit and said turbine,

an operating medium to said turbine, a ho]- electrode and being directly coupled with liquid into thespace between said positive electrode and said tube.

3. In an arc lamp in combination two electrodes and holders therefor, circuits for connecting said electrodesto a current source, a motor, a tube s aced around the positive electrode and being directly coupled with said motor, and means for supplying cooling liquid into the space between said ositive electrode and said tube, and means or also cooling the negative electrode.

4. In an arc lamp in combination two electrodes and holders therefor, means for connecting said electrodes to a current source, a turbine a tube spaced around the positive electrode and being directly coupled with said turbine, means for supplying cooling liquid into "the space between said ositive electrode and said tube, and means or supplying an operating medium to said turbine. 5. In an arc lamp' in combination two electrodes and holders therefor, means for connecting said electrodes to a current source, a turbine, a tube spaced around the positive electrode and being directly coupled with said turbine, means for supplying cooling liquid into the s ace between said positive electrode and sai tube, means for supplying an operatingmedium to said turbine, and means for conductin the operating medium discharged from sai turbine to the negative electrode for cooling said electrode.

' 6. In an arc lamp in combination two electrodes and holders therefor, circuits for connecting said electrodes to a current source, a

motor, a tube spaced around the positive electrode and being directly coupled with said motor, and means for 'supplyin cooling liquid into the space between said positive electrode and said tube, an arm connecting said electrode holders, 1y elements forholddz; in place and yielding elements inserted in said guy elements for compensating the expansion and contrac-' tion of said guy elements due to variations in temperature.

7. In an arc lamp in combination two elec: trodes and holders therefor, means for connecting said electrodes to a current source, a turbine, a tube spaced around the positive electrode and being directly coupled with means for supplying cooling liquid into the s ace between said positive e'lectrodeand sai tube, means for supplying low arm for connectin the two electrode holders togetherand being adapted to conduct the operating medium discharged by said turbine to the negative electrode holder forcooling the negative electrode.

8. In an arc lamp in combination two electrodes and holders therefor, circuits for connecting said electrodes to acurrent source, a motor, a tube spaced, around the positive said motor, and means for supplying cooling liquid into the s ace between said'positive electrode'andsai tube, a cut-out switch in the circuits including said electrodes and control means for said switchresponsive to the speed of said rotating tube for interrupting the current supply to said electrodes when the speed of the tube drops below a desired permissible limit.

1o 9. In an arc lamp in combination two electrodes and holders therefor, circuits for connecting said electrodes to a current source, a motor, a tube spaced around the positive electrode and being directly coupled with said motor, means for guiding coolin liquid into the'space between said positivee ectrode and I said tube and means'operated by said motor for supplying the cooling liquid to said guidmg means.

In testimony whereof .we afiix our signatures. OTTO KRELL. HANS GERDIEN. 

